Jon M Sterling, a computer scientist at Cambridge University, has created his own ‘mathematical Zettelkasten’, which he also calls ‘a forest of evergreen notes’.
He maintains a very interesting website, built using a tool he created, named, appropriately enough, Forester.
The implementation of his ideas raises all sorts of ideas and questions for me, almost all enthusiastic. Here are a few in no order at all:
Andy Matuschak coined the term ‘evergreen notes’, which Jon Sterling has further developed with great elegance.

Before seeing Jon Sterling’s site, I had held a simple distinction between the Zettlekasten and the Wiki. I don’t really wish to re-open an old argument, but just want to make a small observation. For me, a Wiki is a public- or semi-public facing product in its own right, a kind of publication, whereas a Zettelkasten is a method or process to produce public-facing artifacts, but it isn’t one of these artifacts itself. But now I wonder whether you can’t do both back-stage and front-stage at the same time. In other words, it looks to me like Jon Sterling is creating a Zettelkasten by my definition (it’s a process to produce public-facing artifacts such as articles and presentations), but he’s working with the garage door open (it’s a kind-of product in its own right). This is an interesting thing to watch, and it’s always fun to experience the mystique of the studio.